摘要：This study reports the performance of a pilot scale, moving sand-bed filtration unit for surface water treatment. The unit with a capacity of about 7 m3 h-1 was erected at the premises of Fostat water treatment plant in Cairo for the treatment of the water for potable use from the river Nile. During an observation period of 5 months, the dynamic sand filtration unit exhibited a stable performance in terms of removal of turbidity and algae and maintenance of appropriate levels of chemical agents added for aiding the treatment process (alum, chlorine). Under the same loading, the performance of the newly introduced unit was better than or comparable to that of the existing treatment unit (pulsator followed by filtration) at that site. As compared to a high turbidity of 3-14 NTU of the raw Nile water, the turbidity of the treated water was in the range of 0.2-1 NTU. The performance of the dynamic sand filtration unit, unlike that of the existing treatment unit, was not influenced by the high algae content (4000-9000 algae count) of the raw water. The algae count in the treated water was around 100. The unit also maintained, in the treated water, appropriate levels of chemical agents (alum, chlorine) which were added for treatment. The residual alum and chlorine concentrations in the treated water ranged around 0.2 and 1-2.5 ppm, respectively. The effluent from the unit convincingly conformed to the local standards.
